1. Field of the Invention
The invention relates to a sealing arrangement comprising a one-piece sealing ring with a parting joint and compensating clearance and cover ring surrounding or enclosing the sealing ring in the peripheral direction.
2. Description of the Prior Art
Sealing arrangements for a body of circular cross-section such as a piston rod are known, in particular for piston compressors. Dry running piston compressors are machines which require no foreign lubrication in the compression part. Such compressors have fixed sealing elements past which a piston rod is moved. The seal elements are usually arranged one after the other in series and form in this manner a so-called packing. A packing of this type with sealing arrangements and sealing rings is known from CH 439 897. Sealing rings are subject to wear at the sealing surface which lies against the piston rod. In order to maintain the sealing function over longer periods of time, the known sealing ring has wear compensation wherein the sealing ring is split up into three sealing ring elements with partial joints extending parallel to a tangent with respect to the piston rod and with radial joints forming a compensatory ring gap. A hose spring peripherally surrounding the sealing ring exerts a preload on the sealing ring elements towards the piston rod. This known sealing arrangement has the disadvantage that the sealing ring has a large number of partial joints, which impair the sealing function. In order to seal off these joints, a cover ring lying in contact in the axial direction is arranged adjacent to the sealing ring. Such a sealing arrangement has the disadvantage that it has a relatively long extent in the axial direction. A known problem of such sealing arrangements at piston rods is the frictional heat which arises. Dissipation of the heat of friction via the seal elements themselves is possible only with difficulty, since the seal elements are usually made of plastic and act thermally almost as insulators. The greatest portion of the heat of friction is thus led off in a clearly less efficient manner by the piston rod. The heat of friction which arises is thus largely responsible for high wear, among other things, when sealing rings of plastic are used. Thus, a complicated and expensive cooling of the packing containing the sealing arrangement is often required.